s390/pkey_pckmo: Return with success for valid protected key types

The key_to_protkey handler function in module pkey_pckmo should return
with success on all known protected key types, including the new types
introduced by fd197556 ("s390/pkey: Add AES xts and HMAC clear key
token support").

Fixes: fd197556 ("s390/pkey: Add AES xts and HMAC clear key token support")
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>